How to approach the modeling of paneling on walls and floors?
This can be done with the Array Modifier and a few modelling tricks. 

First start by adding a defining shape for your panel, in this case it is a wall panel. Make sure that the edges join together properly:



Add an array modifier to see how it tiles and for reference when modelling in the next steps:



Now start adding some details to this shape, beveling edges and doing basic extrusions:



Now start modelling other pieces, like pipes, wiring, etc. and then join it to the mesh using Ctrl+J:





This is the basic technique, feel free to experiment and make it your own. Standard texturing and materials methods apply. I would very much recommend watching the BlenderGuru tutorial on making a space corridor as well.